It's perfectly OK to have a personal project that only you yourself
work on. In fact, most free software projects are like that. A project
with only one contributor, or only a couple, can be quite limited
however. A larger group tends to get more done and, more importantly,
they do different things. A more diverse group brings in more points
of view which tends to make the project better suited to a larger
group of users.

Attracting contributors to a project you've started can be tricky.
Your humble author asked on Twitter and Mastodon for advice on
this very topic, and wrote up a summary on his own blog.

The condensation of the summary is:

Get people over the hump of making their first contribution, by
making it easy and removing all unnecessary obstacles. Make
contributing into a rewarding experience.

Obstacles can be things like making it difficult to install, run, or
use the software, making it difficult to find, retrieve, or
understand the source code, not having public discussion forums
(mailing lists, IRC channels, etc), or not having a public ticketing
system.